The present invention relates to a portable reinforcing bar binding device for binding reinforcing bars, laid down laterally and longitudinally at construction sites, by a wire at their intersections.
Hitherto, as the means for improving the reinforcing bar binding work at construction sites, a reinforcing bar binding device as shown in FIG. 29 has been proposed (Japanese Patent Publication No. 5-13223). This reinforcing bar binding device has a J-shaped loop forming unit 102 provided at the leading end of a main body 101, and a wire reel 103 provided at the rear part of the main body 101, and the loop forming unit 102 is moved back and forth by a reciprocal driving mechanism 104, and a wire 105 is sent out from the wire reel 103 by a pair of pinch rollers 107 driven by a motor 106. This wire 105 is further fed into the loop forming unit 102 through a bar-shaped wire twisting unit 110 rotated by a wire cutter 108 driven by solenoid or the like, not shown, and a motor 109. The intersection of reinforcing bars 111 is placed in the loop forming unit 102 in opened state, and the loop forming unit 102 is moved back to close, and the wire 105 is supplied in the loop forming unit 102 to form a wire loop 112, and the wire 105 is cut by the wire cutter 108, and the wire loop 112 is twisted by the wire twisting unit 110.
Furthermore, in other reinforcing bar binding device (Japanese Laid-open Utility Model No. 5-3495 (a microfilm of Japanese Utility Model Application No. 3-51320), by a drive mechanism composed of motors, gears, cams, clutches, rollers, and others, a wire is supplied from the wire reel into the J-shaped loop forming unit to form a wire loop, the wire is cut off, and the wire loop is twisted, and in this reinforcing bar binding device, after supplying the wire into the loop forming unit, it is cut off by a cutter provided near the i-shaped leading end, and the wire loop is formed by hooking and twisting by a hook provided in the bar-shaped wire twisting unit.
In the case of the first reinforcing bar binding device disclosed in Japanese Patent Publication No. 5-13223, four driving devices are used, that is, the reciprocal driving device 104, motor 106, solenoid, and motor 109. As a result, the device is not only bulky but also heavy, and the efficiency of the reinforcing bar binding work by this device is, hence, poor. Besides, the loop is twisted by the bar-shaped loop twisting unit 110. That is, the loop is twisted at its one point. Accordingly, only the portion closer to the loop twisting unit 110 is easily twisted, and the height of the twisted portion of the loop is increased. As a result, when the reinforcing bar is buried in concrete, this wire twisted portion is exposed, and corrosion of reinforcing bar may be originated from this exposed portion. Moreover, the intersection of reinforcing bars must be bound by forming loops plural times by the wire, but in the case of this reinforcing bar binding device, it seems difficult to form loops of wire plural times.
In the case of the second reinforcing bar binding device mentioned above, after forming a wire loop, the wire is cut off near the leading end of the J-shaped loop forming unit considerably remote from the loop twisting unit. Accordingly, according to the example disclosed in the microfilm of Japanese Utility Model Application No. 3-51329, at least 3/4 of the periphery of the wire loop is displaced out of the twisted portion of the wire, and it is a wasteful portion.
In this reinforcing bar binding device, too, same as in the first reinforcing bar binding device, the wire loop is twisted at its one point by the bar-shaped loop twisting unit. Accordingly, same as above, the twisted portion of the wire loop is high, and the wasteful portion is further extended above the twisted portion, and the wire is exposed from the concrete, which gives rise to corrosion of reinforcing bar.
Moreover, in this reinforcing bar binding device, various mechanical elements are used in the driving mechanism, such as motor, gears, cam, clutch and rollers, and the structure is too much complicated.
The invention is devised to solve the problems of such prior arts, and it is an object thereof to present a reinforcing bar binding device of simple structure and light weight, capable of preventing exposure of wire from the concrete which may cause corrosion of reinforcing bar, by reducing the height of the twisted portion of wire.